Thank you Baze for the response! Yes I have contacted them directly and they said that because it's a points/money combo booking I need to contact the Honors line. I am trying to shorten the end of the stay by one day. I think I can probably sort it out there but would prefer to sort it here since I will be jet lagged and running ragged with kids at Disneyland. So far I am finding their customer service line lacking, and the selling of time shares at the end of each call is a bit tacky in my humble opinion.

(Originally I needed to add one day to beginning and then shorten end, but finally worked out with the hotel that I could just book a new reservation for one night at the beginning and they will keep me in that room when the other reservation starts... just need to shorten the end...)